The lumbering, shaggy-haired woolly mammoth once thrived in the frigid Arctic plains despite having originally migrated from a more tropical climate. A new study has found tiny genetic mutations that changed the way oxygen was delivered by its blood could be responsible for its tolerance to the cold climate.

The woolly mammoth was an elephantid species and most closely related to today's Asian elephants. It went extinct around 13,000 years ago. But because the mammoth lived in the Arctic, many remains of the species have been found preserved in the permafrost.

Ancestors of both the mammoth and Asian elephant originated in Africa around 6.7 million to 7 million years ago and stayed for about 4 million years before moving up into Southern Europe and then farther up into what is now Siberia and the northern plains of Canada around a million years later.